ACUS11 KWNS 122307
SWOMCD
SPC MCD 122306=20
SDZ000-NEZ000-130100-

Mesoscale Discussion 1974
NWS Storm Prediction Center Norman OK
0606 PM CDT Sat Aug 12 2023

Areas affected...southwestern South Dakota

Concerning...Severe Thunderstorm Watch 637...

Valid 122306Z - 130100Z

The severe weather threat for Severe Thunderstorm Watch 637
continues.

SUMMARY...An isolated supercell may be maintained with a continued
slow southeastward propagation into the Pine Ridge Reservation
through 6-8 PM MDT, accompanied by large hail, locally strong
surface gusts and perhaps some increasing risk for a tornado.

DISCUSSION...An isolated supercell is in the process of propagating
southeast of the Black Hills, embedded within a rather modest
(around 20 kt), but strongly sheared westerly deep-layer mean flow.=20
Likely aided by lift forced by a zone of enhanced lower/mid
tropospheric warm advection, and moderately strong southeasterly
near-surface inflow characterized by mixed-layer CAPE around 2000
J/kg, it appears this activity will be maintained for at least
several more hours.=20=20

A slow southeastward propagation across the Badlands into the Pine
Ridge Reservation should persist, accompanied by a continuing risk
for large hail and locally damaging wind gusts. Some strengthening
of south-southeasterly ambient flow around 850 mb through 00-02Z may
contribute to at least some risk for a tornado.

..Kerr.. 08/12/2023

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!8_ExNNUI-C_MEvvhYw1FWl2bpcjVDLrlbM59AdGGUByfEspudmmHiJdFp3HgNkZ73o2QQCdq4= c_oodgSKfy_4TKtAuo$ for graphic product...

ATTN...WFO...LBF...UNR...CYS...

LAT...LON 43950263 43160153 42930260 43040309 43290333 43950263=20


=3D =3D =3D
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